1. Field
This disclosure relates to a rechargeable lithium battery.
2. Description of the Related Technology
Recently, rechargeable lithium batteries have drawn attention as a power source for small portable electronic devices. Rechargeable lithium batteries use an organic electrolyte solution and have twice or more the discharge voltage than that of conventional batteries using an alkali aqueous solution.
As for a positive active material for a lithium rechargeable battery, a lithium-transition element composite oxides being capable of intercalating lithium, such as LiCoO2, LiMn2O4, LiNi1−xCoxO2 (0<x<1), and the like, has been investigated. As for a negative active material for a lithium rechargeable battery, various carbon-based materials such as artificial graphite, natural graphite, and hard carbon capable of intercalating and deintercalating lithium ions have been used. Since graphite among the carbon-based materials has a low discharge potential relative to lithium of about −0.2V, a battery using the graphite as a negative active material has a high discharge potential of about 3.6V and excellent energy density. Furthermore, the graphite imparts a long cycle life for a battery due to its outstanding reversibility. However, a graphite active material has a low density (theoretical density: about 2.2 g/cc) and consequently a low capacity in terms of energy density per unit volume when using the graphite as a negative active material.
Further, a battery may swell and thus, decreased capacity, because graphite can react with an electrolyte at a high discharge voltage. In order to solve these problems, an oxide negative active material such as tin oxide, lithium vanadium-based oxide, and the like has been investigated. However, the oxide negative active material may not realize sufficient cell performance.